The functional reason to distinguish the two, it seems to me, is in the conversational nature of the game. People will take your move as legitimate, but will generally want to add something to it.

A lot of established game groups have this structure, that you can say something happens, but others have the right to fill in certain details of what happens.

Except in something like microscope, there isn’t a sort of “action, your turn, action” structure, as even within your turn, you are taking on other people’s input, implicitly or explicitly.

And so in that context, “yes you do it, but how does it turn out” is a way of respecting other people’s contributions in the whole while putting a twist on them, and the idea that contributions will often be accepted but still take a twist is vastly important (at least when introducing people to roleplaying games).

If you add on to that details about where we expect someone to have less or more control, where there are different expectations of following someone exactly and checking what they meant, vs jumping off it and seeing what it inspires, or where the dice or counters get involved and we adjust something automatically, you can get back to the conventional definition of “I drop two cards to avoid the danger” “as I do this tension increases by one” etc.